title: Verbal and visual stimulation effects on rectus femoris and biceps femoris muscles during isometric and concentric.
abstract: BACKGROUND
  Coactivation may be both desirable (injury prevention) or undesirable (strength measurement). In this context, different styles of muscle strength stimulus have being investigated. In this study we evaluated the effects of verbal and visual stimulation on rectus femoris and biceps femoris muscles contraction during isometric and concentric.
  
  
  METHODS
  We investigated 13 men (age =23.1 ± 3.8 years old; body mass =75.6 ± 9.1 kg; height =1.8 ± 0.07 m). We used the isokinetic dynamometer BIODEX device and an electromyographic (EMG) system. We evaluated the maximum isometric and isokinetic knee extension and flexion at 60°/s. The following conditions were evaluated: without visual nor verbal command (control); verbal command; visual command and; verbal and visual command. In relation to the concentric contraction, the volunteers performed five reciprocal and continuous contractions at 60°/s. With respect to isometric contractions it was made three contractions of five seconds for flexion and extension in a period of one minute.
  
  
  RESULTS
  We found that the peak torque during isometric flexion was higher in the subjects in the VVC condition (p > 0.05). In relation to muscle coactivation, the subjects presented higher values at the control condition (p > 0.05).
  
  
  CONCLUSIONS
  We suggest that this type of stimulus is effective for the lower limbs.
authors.affiliation: Universidade do Vale do Paraíba, Av, Shishima Hifumi, 2911 Urbanova, 12244-000 São José dos Campos, SP, Brasil. acaropmd@gmail.com.
authors.forename: Sidney B
authors.initials: SB
authors.lastname: Silva
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: de Abreu
authors.forename: Vitor E
authors.initials: VE
authors.lastname: Valenti
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Nogueira
authors.forename: Eder R
authors.initials: ER
authors.lastname: Moraes
authors.forename: Vilma
authors.initials: V
authors.lastname: Natividade
authors.forename: Paulo Rogério
authors.initials: PR
authors.lastname: Gallo
authors.forename: Dafne
authors.initials: D
authors.lastname: Herrero
authors.forename: Patrícia M D
authors.initials: PM
authors.lastname: Zacaro